The Twin Cities Household Ecosystem Project: A unique survey approach for studying household biogeochemical cycling

Background/Question/Methods

Households often account for a major fraction of carbon (C), nitrogen (N), and phosphorus (P) fluxes through post-industrial cities. Because of this, we need to understand drivers of household biogeochemistry in order to fully conceptualize urban biogeochemical cycling, but the methodologies for this complex system are not fully developed. Ultimately, we seek to integrate human behavior into a model of urban biogeochemistry. Households are valuable units of study in cities because (1) cumulatively, household fluxes are an important component of total urban fluxes of macroelements such as C, N, and P; (2) many household fluxes are flexible; and (3) understanding household choices could inform policies intended to reduce consumption of resources or production of pollutants. The goal of the Twin Cities Household Ecosystem Project (TCHEP) is to understand coupling between household biogeochemical fluxes and socioeconomic factors along an urban-to-exurban gradient in the Minneapolis-Saint Paul (Twin Cities) metropolitan area, Minnesota.

Results/Conclusions

We designed and implemented a mail survey of single-family, owner-occupied, detached homes along an urban-exurban gradient. This poster focuses on the methodologies of the TCHEP survey and the contributions to an integrating Household Flux Calculator that estimates element fluxes associated with home energy use, air and car travel, diet, pets, paper and plastics, and vegetation. Our conceptual boundary for a household included the physical property of each household plus all personal transportation by household occupants. Using a modified Dillman method, we sent mail surveys to randomly selected homes in the sample frame and received approximately 3,000 responses, supporting generalizable findings; 2,000 of these respondents provided access to their energy records.  We then conducted a field survey of vegetation at 400 randomly chosen respondent households.  A key conclusion is that the unique TCHEP methodology, a hybrid approach that includes a mail survey, permission to access utility records, ground-based sampling, and readily available GIS data, can be used to estimate C, N, and P fluxes for large numbers of households. The simultaneous collection of demographic characteristics and behavioral attributes has allowed us to examine relationships between elemental fluxes and consumption behaviors in these households.